The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry utilized various methods and structures to produce pulse width modulated (PWM) power supply controllers. In some cases, the power supply controllers monitored the average value of a bulk input voltage to determine if the bulk input voltage was sufficient to form a desired output voltage. These types of controllers also relied on a ripple voltage on the bulk input voltage in order to provide the protection. In most cases, the monitors and sensors did not have sufficient accuracy. As a result, the bulk input voltage value at which the PWM controller went into a protection mode varied. The inaccurate detection often resulted in damage to the power supply controller.
Accordingly, it is desirable to have a PWM controller that more accurately senses the bulk input voltage, and that protects the power supply controller.
For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action. The use of the word approximately or substantially means that a value of an element has a parameter that is expected to be very close to a stated value or position. However, as is well known in the art there are always minor variances that prevent the values or positions from being exactly as stated. It is well established in the art that variances of up to about ten per cent (10%) (and up to twenty per cent (20%) for semiconductor doping concentrations) are regarded as reasonable variances from the ideal goal of exactly as described.